Polycarbonate resin is a representative thermoplastic material that has a heat deflection temperature of about 135° C. or higher and can exhibit superior mechanical properties including impact resistance, and excellent self-extinguishing properties, dimensional stability, heat resistance and transparency. Thus, polycarbonate resins are widely used in various applications, such as exterior materials of electronic and electric products, automobile components, and the like.
However, despite excellent transparency and mechanical properties, polycarbonate has limitations in use for exterior materials. When a plastic material is used as an exterior material, the product is often coated to enhance the aesthetics thereof. In this case, a dye diluted with various organic solvents can be applied to the surface of a molded resin article and dried. The organic solvents used as diluents can penetrate into the polycarbonate, which can decrease transparency and mechanical strength. Thus, in order to use polycarbonate in products frequently exposed to various organic solvents in the course of use, it is important for the polycarbonate to have resistance against these organic solvents.
Korean Patent Publication Nos. 2007-0071446A, 2009-0026359A and 2010-0022376A disclose methods for improving chemical resistance of a polycarbonate resin by blending with other resins having chemical resistance. Although such methods may slightly improve chemical resistance, these methods can cause deterioration in impact resistance. Further, in order to enhance impact resistance deteriorated by blending, an impact reinforcing agent may be employed. In this case, however, significant decrease in transparency of the resin can be encountered.
Japanese Patent Publication No. H5-339390A and U.S. Pat. No. 5,401,826 disclose a method for improving chemical resistance by manufacturing a copolymerized polycarbonate in which a material having chemical resistance is incorporated into a conventional polycarbonate resin.
As one example of the chemically resistant material to be copolymerized, 4,4′-biphenol is used in the copolymerization of polycarbonate resins, thereby improving chemical resistance. The polycarbonate resin may have improved chemical resistance by the use of 4,4′-biphenol, however, impact resistance of the resin may be lowered, thereby deteriorating the merits of the polycarbonate resin. As the amount of 4,4′-biphenol increases, fluidity of the resin is drastically decreased, thereby deteriorating moldability.
In addition, since the conventional polycarbonate has had a bad scratch resistance, it has been often used to blend with PMMA and the like. In this case, the polycarbonate is badly compatible with PMMA, and thus, it may result in deteriorating the other physical properties.
Therefore, there is need for developing polycarbonate having excellent self-scratch resistance.